The present invention generally related to devices and methods of distraction, particularly of connective tissue such as bone, such as in a human subject. Preferably, the devices and methods are used in human craniofacial bone distraction.
Connective tissue is the tissue that binds together and supports the various structures of the body. It has been demonstrated that gradual application of force separating two or more portions of a canine or human connective tissue structure will result in deposition of extra cellular fibrous tissue components with permanent increase in tissue size and mass. E.g., Karp, N. S., McCarthy, J. G., Schneiber, J. S., Sissons, H. A., and Thome, C. H. M., xe2x80x9cMembranous Bone Lengthening: A Serial Histological Study,xe2x80x9d 29 Ann. Plast. Surg. 2-7 (1992); and Costantino, P. D. and Freidman, C. D., xe2x80x9cDistraction Osteogenesis,xe2x80x9d 24 Otolaryngologic Clinics of N.A. 1433-43 (1991) (xe2x80x9cCostantino et al.xe2x80x9d). In some instances this has been facilitated by cutting or breaking the tissue intermediate the tissue areas where force is applied by performing an osteotomy or corticotomy. In other instances, particularly involving growing tissue, such cutting or breaking is not necessary.
For instance, human bone lengthening by gradual distraction was demonstrated at least as early as 1905, but it has been more widely practiced only more recently, having been popularized by Ilizarov in Russia and De Bastiani and his associates in Italy. See McCarthy, J. G., Schneiber, J., Karp, N., Thorne, C. H., and Grayson, B. H., xe2x80x9cLengthening the Human Mandible by Gradual Distraction,xe2x80x9d 89 Plast. And Reconstruct. Surg. 1-8 (1992) (xe2x80x9cMcCarthy et al.xe2x80x9d); and Ilizarov, xe2x80x9cThe Principles of the Ilizarov Method,xe2x80x9d 48 Bull. of the Hospital for Joint Diseases Orthopaedic Institute 1-11 (1988). Gradual distraction offers distinct advantages as compared to bone grafting. Taylor, Discussion of McCarthy et al., 89 Plast. and Reconstruc. Surg. 9-10 (1992):
It provides new living bone of similar character, the soft tissues are lengthened without loss of sensation, there is no donor-site morbidity, and the technique may stimulate the efficiency of the reduced functional matrix in the region. Id. At 10.
Most bone lengthening and corrective work has been done with respect to long bones in the arms and legs, although McCarthy, et al. have demonstrated that the mandible of human children can be lengthened by gradual distraction. See also Senezer, M., xe2x80x9cMandibular Lengthening by Gradual Distraction,xe2x80x9d 92 Plast. and Reconstruct. Surg. 372 (1993) (reporting lengthening of human adult mandibles).
Additionally, devices utilizing screw or other expansion mechanisms attached between and solely to the left and right maxillary teeth have been used in procedures that enlarge human palates. e.g, Epker, B., and Fish, L., 2 Dental Facial Deformities 818-875 (1986). At least some such procedures commence with substantial expansion of the maxilla during the initial surgical procedure. Id. At 831.
The mandibular distraction device utilized by McCarthy, et al., is a relatively large appliance mounted outside the patient""s mouth on pins that pass through incisions in the cheek. Such distraction devices are heavy, unwieldy, unsightly and subject to damage or dislocation impact. Furthermore, such devices require incisions that leave scars that may be unsightly and require revision. As McCathy et al. have noted, better mandibular distraction devices are needed for these and other reasons. See also Costantino et al. at 1441; and Karp, N. S., Thome, C. H. M., McCarthy, J. G., Sissons, H. A., xe2x80x9cBone Lengthening in the Craniofacial Skeleton,xe2x80x9d 24 Ann. Plast. Surg. 231, 236 (1990). Furthermore, gradual distraction of other craniofacial sites is desirable but generally has not been possible because of the limitations of existing devices.
Early midface distraction with buried devices were being performed in various centers by about 1993 (Cohen et al., J. Craniofac. Surg. 6:368 etc. (1995); Muhlbauer, Reconstructive and Aesthetic Surg. Meeting, Yokahoma, Japan, April 1995 (abstract)). Molina performed high Le Fort I osteotomoies and midface distraction by a reverse headgear that had the characteristics of a tooth-borne appliance (Molina, Workshop on Distraction of the Craniofacial Skeleton, New York University Medical Center, New York, N.Y., Mar. 18-19 (1994)). In addition, buried midface distraction was performed in a child with anophthalmia and left craniofacial micrisomia (Cohen et al., Craniofac. Sur. 6:368 etc. (1995)). In this instance, the outcomes were documented by cephalograms and coronal or three-dimensional computed tomographic scans. Muhlbauer conducted a series of Le Fort III and monobloc distraction in patients with Apert""s syndrome (International Meeting of Plastic, Reconstructive, and Aesthetic Surgery in Yokohama, Japan (1995)). Chin and Toth reported buried distraction, including Le Fort III midfacial advancement (Chin and Toth, J. Oral Maxillofac. Surg. 54:45 etc. (1996)). Polley et al., using an external traction appliance, showed frontofacial advancement in a newborn with proptosis and upper airway obstruction (Polley et al., J. Craniofac. Surg. 6:421-423 (1995)). Buried modified Le Fort III midface advancements having cleft lip and palate with midface hypoplasia and Class III maloccluson have been performed (Cohen et al., Plast. Reconstr. Surg. 99:1421-1428 (1997)). In these cases, transverse maxillary expansion was performed with sagittal distraction and in one case serial distractors were used to provide vertical and horizontal distraction vectors. In other cases, a subtotal cranial vault reshaping and monobloc facial advancement was performed in a child who had Pfeiffer""s syndrome and coreal exposure (Cohen et al., Plast. Reconstr. Surg, 101:1919-1924 (1998)). In that case, after 28 mm of distraction, the proptosis was largely corrected. Chin and Toth have reported Le Fort III advancement with gradual distraction using internal devices in a series of patients using a method of rapid distraction (Chin and Toth, Plast. Reconstr. Surg. 100:819-830 (1998)). Polley and Figueroa reported the management of maxiallary deficiency in childhood and adolescence by performing distraction osteogenesis with an external adjustable, rigid distraction device to provide improvement in cleft lip, cleft palate and severe midface retrusion (Polley and Figueroa, J. Craniofac. Surg. 78:181-185 (1997); See generally Cohen, Seminars in Orthodontics, 5:52-58 (1999)).
Additional explanation of the conditions addressed by the present invention and, in some instances, more specific information about prior remedial practices is set forth together with the descriptions of exemplary embodiments of the present invention provided below.